1. Field of the Invention
This invention relates generally to cellular communication devices and more particularly to cellular speakerphones.
2. Description of the Related Art
Radio frequency (RF) communication systems, such as cellular radiotelephone systems, permit a user to communicate from locations within a broad area. Commercially available cellular radiotelephones include both portable units that can be carried by the user and mobile units that are permanently mounted to a vehicle. Each of the aforementioned cellular radiotelephones has characteristics that make it preferable with respect to the other.
Portable cellular radiotelephones, such as MicroTac.TM. radiotelephones manufactured and sold by Motorola, Inc., are revered for their compact size. These cellular radiotelephones include a housing containing a transceiver circuit and a user interface. The user interface includes a keypad, a display, a microphone, and a speaker. The portable cellular radiotelephone is typically powered by a rechargeable battery which is attached to the housing to provide operating power and detached once depleted for recharging. Therefore, portable cellular telephones must be made to operate at low power so as to increase the time period between recharging.
Mobile cellular radiotelephones, such as the Series IV Cellular Mobile Transceiver radiotelephone manufactured and sold by Motorola, Inc., are permanently mounted within a vehicle or transported within a shoulder bag and powered via the vehicle's electrical system. As a result, the mobile cellular radiotelephone may operate at a higher power level than the portable cellular radiotelephone without detrimentally affecting its operating time while benefiting from an increased transmission range.
To augment ease of operation, hands-free accessories are utilized in conjunction with both portable and mobile cellular radiotelephones. Hands-free accessories are attachable external apparatuses that allow the portable or mobile cellular radiotelephone to function in a manner similar to a conventional speaker phone. This provides the user with free use of his/her hands for other activities, such as taking notes, during a cellular radiotelephone call. Motorola, Inc. does not condone conversing on a cellular radiotelephone while driving, an action that is unlawful in some states.
Therefore, there is a need for a cellular radiotelephone that benefits from the advantages of each of the portable cellular radiotelephones, mobile cellular radiotelephones, and hands-free accessories.